Browse Publications Technical Papers 2022-01-0434

Increasing the Effective AKI of Fuels Using Port Water Injection (Part II) 2022-01-0434

This is the second part of a study on using port water injection to quantifiably enhance the knock performance of fuels. In the United States, the metric used to quantify the anti-knock performance of fuels is Anti Knock Index (AKI), which is the average of Research Octane Number (RON) and Motor Octane Number (MON). Fuels with higher AKI are expected to have better knock mitigating properties, enabling the engine to run closer to Maximum Brake Torque (MBT) spark timing in the knock limited region. The work done in part I of the study related increased knock tolerance due to water injection to increased fuel AKI, thus establishing an ‘effective AKI’ due to water injection. This paper builds upon the work done in part I of the study by repeating a part of the test matrix with Primary Reference Fuels (PRFs), with iso-octane (PRF100) as the reference fuel and lower PRFs used to match its performance with the help of port water injection. Additionally, the unburned gas pressure-temperature trajectories for varying loads were analyzed to better understand the underlying physics of port water injection in engines. Finally, a comparison was made between the amount of water and excess fuel required to gain a similar increase in effective AKI.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 16% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Experimental and Simulation Analysis of 1.3 Litre Water Cooled Engine Lubrication Circuit


View Details


Evaluating the Benefits of On-Board Measurement of Ambient Humidity Part-1: Effect on Spark Timing and Combustion Efficiency


View Details


An Optical Sensor for Determination of Combustion Parameters in a Natural Gas Fuelled Spark Ignition Engine


View Details